Woodward HighPROtec MCDLV4, Manual

Page: 494 / 1275

Module: Protection (Prot)
Directional Features for Calculated (IG calc) Ground Fault 50N/51N
All ground fault elements can be selected as »
non-directional/forward/reverse« operated. This has to be done in
the »
Device Planning« menu.
Important Definitions
Polarizing Quantity: This is the quantity that is used as a reference value.
The polarizing quantity can be selected
by the parameter » IG calc dir ctrl« in the [Field Para/Direction] menu as follows:
»IG calc 3V0«: The neutral voltage selected by the parameter »3V0 Source« will be used
as the polarizing quantity. The traditional way to polarize a ground fault element is to use
neutral voltage (3V0). The neutral voltage can, however, be either »
measured« or
» calculated«. This can be selected by the parameter »3V0 Source« in the [Field
Para/Direction] menu.
»IG calc Ipol (IG meas)«: The measured neutral current (usually = IG meas) will be used
as polarizing quantity.
»Dual«: For this method, the measured neutral current Ipol=IG meas will be used as
polarizing quantity, if available, otherwise 3V0 will be used.
»I2,V2«: With this selection, the negative phase sequence voltage and current will be used
to detect the direction. The monitored current is still the calculated residual current IG
calc.
Operating Quantity:
For the directional IG calc elements, the
operating quantity is in general the calculated neutral
current IG calc (except from »I2,V2« mode, where »I2« is the operating quantity).
The ground maximum torque angles (MTA) can be adjusted from 0° to 360°, except, if »
IG calc Ipol (IG meas)« is
selected. In this case it is set to 0° (fixed).
The MTA will also be set internally to 0° in case that Ipol=IG meas is available within the Dual-Mode
494 MCDLV4 DOK-HB-MCDLV4-2E